Brooklyn/plasma/workspace/libtaskmanager/tasksmodel.h

/*
    SPDX-FileCopyrightText: 2016 Eike Hein <hein@kde.org>

    SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
*/

#pragma once

#include <QQmlParserStatus>
#include <QSortFilterProxyModel>

#include "abstracttasksmodeliface.h"

#include "taskmanager_export.h"

namespace TaskManager
{
/**
 * @short A unified tasks model.
 *
 * This model presents tasks sourced from supplied launcher URLs, startup
 * notification data and window data retrieved from the windowing server
 * the host process is connected to. The underlying windowing system is
 * abstracted away.
 *
 * The source data is abstracted into a unified lifecycle for tasks
 * suitable for presentation in a user interface.
 *
 * Matching startup and window tasks replace launcher tasks. Startup
 * tasks are omitted when matching window tasks exist. Tasks that desire
 * not to be shown in a user interface are omitted.
 *
 * Tasks may be filtered, sorted or grouped by setting properties on the
 * model.
 *
 * Tasks may be interacted with by calling methods on the model.
 *
 * @author Eike Hein <hein@kde.org>
 **/

class TASKMANAGER_EXPORT TasksModel : public QSortFilterProxyModel, public AbstractTasksModelIface, public QQmlParserStatus
{
    Q_OBJECT
    Q_INTERFACES(QQmlParserStatus)

    Q_PROPERTY(int count READ rowCount NOTIFY countChanged)
    Q_PROPERTY(int launcherCount READ launcherCount NOTIFY launcherCountChanged)

    Q_PROPERTY(QStringList launcherList READ launcherList WRITE setLauncherList NOTIFY launcherListChanged)

    Q_PROPERTY(bool anyTaskDemandsAttention READ anyTaskDemandsAttention NOTIFY anyTaskDemandsAttentionChanged)

    Q_PROPERTY(QVariant virtualDesktop READ virtualDesktop WRITE setVirtualDesktop NOTIFY virtualDesktopChanged)
    Q_PROPERTY(QRect screenGeometry READ screenGeometry WRITE setScreenGeometry NOTIFY screenGeometryChanged)
    Q_PROPERTY(QString activity READ activity WRITE setActivity NOTIFY activityChanged)

    Q_PROPERTY(bool filterByVirtualDesktop READ filterByVirtualDesktop WRITE setFilterByVirtualDesktop NOTIFY filterByVirtualDesktopChanged)
    Q_PROPERTY(bool filterByScreen READ filterByScreen WRITE setFilterByScreen NOTIFY filterByScreenChanged)
    Q_PROPERTY(bool filterByActivity READ filterByActivity WRITE setFilterByActivity NOTIFY filterByActivityChanged)
    Q_PROPERTY(bool filterNotMinimized READ filterNotMinimized WRITE setFilterNotMinimized NOTIFY filterNotMinimizedChanged)
    Q_PROPERTY(bool filterNotMaximized READ filterNotMaximized WRITE setFilterNotMaximized NOTIFY filterNotMaximizedChanged)
    Q_PROPERTY(bool filterHidden READ filterHidden WRITE setFilterHidden NOTIFY filterHiddenChanged)

    Q_PROPERTY(SortMode sortMode READ sortMode WRITE setSortMode NOTIFY sortModeChanged)
    Q_PROPERTY(bool separateLaunchers READ separateLaunchers WRITE setSeparateLaunchers NOTIFY separateLaunchersChanged)
    Q_PROPERTY(bool launchInPlace READ launchInPlace WRITE setLaunchInPlace NOTIFY launchInPlaceChanged)

    Q_PROPERTY(GroupMode groupMode READ groupMode WRITE setGroupMode NOTIFY groupModeChanged)
    Q_PROPERTY(bool groupInline READ groupInline WRITE setGroupInline NOTIFY groupInlineChanged)
    Q_PROPERTY(
        int groupingWindowTasksThreshold READ groupingWindowTasksThreshold WRITE setGroupingWindowTasksThreshold NOTIFY groupingWindowTasksThresholdChanged)
    Q_PROPERTY(QStringList groupingAppIdBlacklist READ groupingAppIdBlacklist WRITE setGroupingAppIdBlacklist NOTIFY groupingAppIdBlacklistChanged)
    Q_PROPERTY(QStringList groupingLauncherUrlBlacklist READ groupingLauncherUrlBlacklist WRITE setGroupingLauncherUrlBlacklist NOTIFY
                   groupingLauncherUrlBlacklistChanged)
    Q_PROPERTY(QModelIndex activeTask READ activeTask NOTIFY activeTaskChanged)

public:
    enum SortMode {
        SortDisabled = 0, /**< No sorting is done. */
        SortManual, /**< Tasks can be moved with move() and syncLaunchers(). */
        SortAlpha, /**< Tasks are sorted alphabetically, by AbstractTasksModel::AppName and Qt::DisplayRole. */
        SortVirtualDesktop, /**< Tasks are sorted by the virtual desktop they are on. */
        SortActivity, /**< Tasks are sorted by the number of tasks on the activities they're on. */
    };
    Q_ENUM(SortMode)

    enum GroupMode {
        GroupDisabled = 0, /**< No grouping is done. */
        GroupApplications, /**< Tasks are grouped by the application backing them. */
    };
    Q_ENUM(GroupMode)

    explicit TasksModel(QObject *parent = nullptr);
    ~TasksModel() override;

    QHash<int, QByteArray> roleNames() const override;

    Q_INVOKABLE int rowCount(const QModelIndex &parent = QModelIndex()) const override; // Invokable.

    QVariant data(const QModelIndex &proxyIndex, int role) const override;

    /**
     * The number of launcher tasks in the tast list.
     *
     * @returns the number of launcher tasks in the task list.
     **/
    int launcherCount() const;

    /**
     * The list of launcher URLs serialized to strings along with
     * the activities they belong to.
     *
     * @see setLauncherList
     * @returns the list of launcher URLs serialized to strings.
     **/
    QStringList launcherList() const;

    /**
     * Replace the list of launcher URL strings.
     *
     * Invalid or empty URLs will be rejected. Duplicate URLs will be
     * collapsed.
     *
     * @see launcherList
     * @param launchers A list of launcher URL strings.
     **/
    void setLauncherList(const QStringList &launchers);

    /**
     * Returns whether any task in the model currently demands attention
     * (AbstractTasksModel::IsDemandingAttention).
     *
     * @returns whether any task in the model currently demands attention.
     **/
    bool anyTaskDemandsAttention() const;

    /**
     * The id of the virtual desktop used in filtering by virtual
     * desktop. Usually set to the id of the current virtual desktop.
     * Defaults to empty.
     *
     * @see setVirtualDesktop
     * @returns the number of the virtual desktop used in filtering.
     **/
    QVariant virtualDesktop() const;

    /**
     * Set the id of the virtual desktop to use in filtering by virtual
     * desktop.
     *
     * If set to an empty id, filtering by virtual desktop is disabled.
     *
     * @see virtualDesktop
     * @param desktop A virtual desktop id (QString on Wayland; uint >0 on X11).
     **/
    void setVirtualDesktop(const QVariant &desktop = QVariant());

    /**
     * The geometry of the screen used in filtering by screen. Defaults
     * to a null QRect.
     *
     * @see setGeometryScreen
     * @returns the geometry of the screen used in filtering.
     **/
    QRect screenGeometry() const;

    /**
     * Set the geometry of the screen to use in filtering by screen.
     *
     * If set to an invalid QRect, filtering by screen is disabled.
     *
     * @see screenGeometry
     * @param geometry A screen geometry.
     **/
    void setScreenGeometry(const QRect &geometry);

    /**
     * The id of the activity used in filtering by activity. Usually
     * set to the id of the current activity. Defaults to an empty id.
     *
     * @see setActivity
     * @returns the id of the activity used in filtering.
     **/
    QString activity() const;

    /**
     * Set the id of the activity to use in filtering by activity.
     *
     * @see activity
     * @param activity An activity id.
     **/
    void setActivity(const QString &activity);

    /**
     * Whether tasks should be filtered by virtual desktop. Defaults to
     * @c false.
     *
     * Filtering by virtual desktop only happens if a virtual desktop
     * number is set, even if this returns @c true.
     *
     * @see setFilterByVirtualDesktop
     * @see setVirtualDesktop
     * @returns @c true if tasks should be filtered by virtual desktop.
     **/
    bool filterByVirtualDesktop() const;

    /**
     * Set whether tasks should be filtered by virtual desktop.
     *
     * Filtering by virtual desktop only happens if a virtual desktop
     * number is set, even if this is set to @c true.
     *
     * @see filterByVirtualDesktop
     * @see setVirtualDesktop
     * @param filter Whether tasks should be filtered by virtual desktop.
     **/
    void setFilterByVirtualDesktop(bool filter);

    /**
     * Whether tasks should be filtered by screen. Defaults to @c false.
     *
     * Filtering by screen only happens if a screen number is set, even
     * if this returns @c true.
     *
     * @see setFilterByScreen
     * @see setScreen
     * @returns @c true if tasks should be filtered by screen.
     **/
    bool filterByScreen() const;

    /**
     * Set whether tasks should be filtered by screen.
     *
     * Filtering by screen only happens if a screen number is set, even
     * if this is set to @c true.
     *
     * @see filterByScreen
     * @see setScreen
     * @param filter Whether tasks should be filtered by screen.
     **/
    void setFilterByScreen(bool filter);

    /**
     * Whether tasks should be filtered by activity. Defaults to @c false.
     *
     * Filtering by activity only happens if an activity id is set, even
     * if this returns @c true.
     *
     * @see setFilterByActivity
     * @see setActivity
     * @returns @ctrue if tasks should be filtered by activity.
     **/
    bool filterByActivity() const;

    /**
     * Set whether tasks should be filtered by activity. Defaults to
     * @c false.
     *
     * Filtering by virtual desktop only happens if an activity id is set,
     * even if this is set to @c true.
     *
     * @see filterByActivity
     * @see setActivity
     * @param filter Whether tasks should be filtered by activity.
     **/
    void setFilterByActivity(bool filter);

    /**
     * Whether non-minimized tasks should be filtered. Defaults to
     * @c false.
     *
     * @see setFilterNotMinimized
     * @returns @c true if non-minimized tasks should be filtered.
     **/
    bool filterNotMinimized() const;

    /**
     * Set whether non-minimized tasks should be filtered.
     *
     * @see filterNotMinimized
     * @param filter Whether non-minimized tasks should be filtered.
     **/
    void setFilterNotMinimized(bool filter);

    /**
     * Whether non-maximized tasks should be filtered. Defaults to
     * @c false.
     *
     * @see setFilterNotMaximized
     * @returns @c true if non-maximized tasks should be filtered.
     **/
    bool filterNotMaximized() const;

    /**
     * Set whether non-maximized tasks should be filtered.
     *
     * @see filterNotMaximized
     * @param filter Whether non-maximized tasks should be filtered.
     **/
    void setFilterNotMaximized(bool filter);

    /**
     * Whether hidden tasks should be filtered. Defaults to
     * @c false.
     *
     * @see setFilterHidden
     * @returns @c true if hidden tasks should be filtered.
     **/
    bool filterHidden() const;

    /**
     * Set whether hidden tasks should be filtered.
     *
     * @see filterHidden
     * @param filter Whether hidden tasks should be filtered.
     **/
    void setFilterHidden(bool filter);

    /**
     * The sort mode used in sorting tasks. Defaults to SortAlpha.
     *
     * @see setSortMode
     * @returns the current sort mode.
     **/
    SortMode sortMode() const;

    /**
     * Sets the sort mode used in sorting tasks.
     *
     * @see sortMode
     * @param mode A sort mode.
     **/
    void setSortMode(SortMode mode);

    /**
     * Whether launchers are kept separate from other kinds of tasks.
     * Defaults to @c true.
     *
     * When enabled, launcher tasks are sorted first in the tasks model
     * and move() disallows moving them below the last launcher task,
     * or moving a different kind of task above the first launcher. New
     * launcher tasks are inserted after the last launcher task. When
     * disabled, move() allows mixing, and new launcher tasks are
     * appended to the model.
     *
     * Further, when disabled, the model always behaves as if
     * launchInPlace is enabled: A window task takes the place of the
     * first matching launcher task.
     *
     * @see LauncherTasksModel
     * @see move
     * @see launchInPlace
     * @see setSeparateLaunchers
     * @return whether launcher tasks are kept separate.
     */
    bool separateLaunchers() const;

    /**
     * Sets whether launchers are kept separate from other kinds of tasks.
     *
     * When enabled, launcher tasks are sorted first in the tasks model
     * and move() disallows moving them below the last launcher task,
     * or moving a different kind of task above the first launcher. New
     * launcher tasks are inserted after the last launcher task. When
     * disabled, move() allows mixing, and new launcher tasks are
     * appended to the model.
     *
     * Further, when disabled, the model always behaves as if
     * launchInPlace is enabled: A window task takes the place of the
     * first matching launcher task.
     *
     * @see LauncherTasksModel
     * @see move
     * @see launchInPlace
     * @see separateLaunchers
     * @param separate Whether to keep launcher tasks separate.
     */
    void setSeparateLaunchers(bool separate);

    /**
     * Whether window tasks should be sorted as their associated launcher
     * tasks or separately. Defaults to @c false.
     *
     * @see setLaunchInPlace
     * @returns whether window tasks should be sorted as their associated
     * launcher tasks.
     **/
    bool launchInPlace() const;

    /**
     * Sets whether window tasks should be sorted as their associated launcher
     * tasks or separately.
     *
     * @see launchInPlace
     * @param launchInPlace Whether window tasks should be sorted as their
     * associated launcher tasks.
     **/
    void setLaunchInPlace(bool launchInPlace);

    /**
     * Returns the current group mode, i.e. the criteria by which tasks should
     * be grouped.
     *
     * Defaults to TasksModel::GroupApplication, which groups tasks backed by
     * the same application.
     *
     * If the group mode is TasksModel::GroupDisabled, no grouping is done.
     *
     * @see setGroupMode
     * @returns the current group mode.
     **/
    TasksModel::GroupMode groupMode() const;

    /**
     * Sets the group mode, i.e. the criteria by which tasks should be grouped.
     *
     * The group mode can be set to TasksModel::GroupDisabled to disable grouping
     * entirely, breaking apart any existing groups.
     *
     * @see groupMode
     * @param mode A group mode.
     **/
    void setGroupMode(TasksModel::GroupMode mode);

    /**
     * Returns whether grouping is done "inline" or not, i.e. whether groups
     * are maintained inside the flat, top-level list, or by forming a tree.
     * In inline grouping mode, move() on a group member will move all siblings
     * as well, and sorting is first done among groups, then group members.
     *
     * Further, in inline grouping mode, the groupingWindowTasksThreshold
     * setting is ignored: Grouping is always done.
     *
     * @see setGroupInline
     * @see move
     * @see groupingWindowTasksThreshold
     * @returns whether grouping is done inline or not.
     **/
    bool groupInline() const;

    /**
     * Sets whether grouping is done "inline" or not, i.e. whether groups
     * are maintained inside the flat, top-level list, or by forming a tree.
     * In inline grouping mode, move() on a group member will move all siblings
     * as well, and sorting is first done among groups, then group members.
     *
     * @see groupInline
     * @see move
     * @see groupingWindowTasksThreshold
     * @param inline Whether to do grouping inline or not.
     **/
    void setGroupInline(bool groupInline);

    /**
     * As window tasks (AbstractTasksModel::IsWindow) come and go, groups will
     * be formed when this threshold value is exceeded, and  broken apart when
     * it matches or falls below.
     *
     * Defaults to @c -1, which means grouping is done regardless of the number
     * of window tasks.
     *
     * When the groupInline property is set to @c true, the threshold is ignored:
     * Grouping is always done.
     *
     * @see setGroupingWindowTasksThreshold
     * @see groupInline
     * @return the threshold number of window tasks used in grouping decisions.
     **/
    int groupingWindowTasksThreshold() const;

    /**
     * Sets the number of window tasks (AbstractTasksModel::IsWindow) above which
     * groups will be formed, and at or below which groups will be broken apart.
     *
     * If set to -1, grouping will be done regardless of the number of window tasks
     * in the source model.
     *
     * When the groupInline property is set to @c true, the threshold is ignored:
     * Grouping is always done.
     *
     * @see groupingWindowTasksThreshold
     * @see groupInline
     * @param threshold A threshold number of window tasks used in grouping
     * decisions.
     **/
    void setGroupingWindowTasksThreshold(int threshold);

    /**
     * A blacklist of app ids (AbstractTasksModel::AppId) that is consulted before
     * grouping a task. If a task's app id is found on the blacklist, it is not
     * grouped.
     *
     * The default app id blacklist is empty.
     *
     * @see setGroupingAppIdBlacklist
     * @returns the blacklist of app ids consulted before grouping a task.
     **/
    QStringList groupingAppIdBlacklist() const;

    /**
     * Sets the blacklist of app ids (AbstractTasksModel::AppId) that is consulted
     * before grouping a task. If a task's app id is found on the blacklist, it is
     * not grouped.
     *
     * When set, groups will be formed and broken apart as necessary.
     *
     * @see groupingAppIdBlacklist
     * @param list a blacklist of app ids to be consulted before grouping a task.
     **/
    void setGroupingAppIdBlacklist(const QStringList &list);

    /**
     * A blacklist of launcher URLs (AbstractTasksModel::LauncherUrl) that is
     * consulted before grouping a task. If a task's launcher URL is found on the
     * blacklist, it is not grouped.
     *
     * The default launcher URL blacklist is empty.
     *
     * @see setGroupingLauncherUrlBlacklist
     * @returns the blacklist of launcher URLs consulted before grouping a task.
     **/
    QStringList groupingLauncherUrlBlacklist() const;

    /**
     * Sets the blacklist of launcher URLs (AbstractTasksModel::LauncherUrl) that
     * is consulted before grouping a task. If a task's launcher URL is found on
     * the blacklist, it is not grouped.
     *
     * When set, groups will be formed and broken apart as necessary.
     *
     * @see groupingLauncherUrlBlacklist
     * @param list a blacklist of launcher URLs to be consulted before grouping a task.
     **/
    void setGroupingLauncherUrlBlacklist(const QStringList &list);

    /**
     * Finds the first active (AbstractTasksModel::IsActive) task in the model
     * and returns its QModelIndex, or a null QModelIndex if no active task is
     * found.
     *
     * @returns the model index for the first active task, if any.
     */
    QModelIndex activeTask() const;

    /**
     * Request adding a launcher with the given URL.
     *
     * If this URL is already in the list, the request will fail. URLs are
     * compared for equality after removing the query string used to hold
     * metadata.
     *
     * @see launcherUrlsMatch
     * @param url A launcher URL.
     * @returns @c true if a launcher was added.
     */
    Q_INVOKABLE bool requestAddLauncher(const QUrl &url);

    /**
     * Request removing the launcher with the given URL.
     *
     * If this URL is already in the list, the request will fail. URLs are
     * compared for equality after removing the query string used to hold
     * metadata.
     *
     * @see launcherUrlsMatch
     * @param url A launcher URL.
     * @returns @c true if the launcher was removed.
     */
    Q_INVOKABLE bool requestRemoveLauncher(const QUrl &url);

    /**
     * Request adding a launcher with the given URL to current activity.
     *
     * If this URL is already in the list, the request will fail. URLs are
     * compared for equality after removing the query string used to hold
     * metadata.
     *
     * @see launcherUrlsMatch
     * @param url A launcher URL.
     * @returns @c true if a launcher was added.
     */
    Q_INVOKABLE bool requestAddLauncherToActivity(const QUrl &url, const QString &activity);

    /**
     * Request removing the launcher with the given URL from the current activity.
     *
     * If this URL is already in the list, the request will fail. URLs are
     * compared for equality after removing the query string used to hold
     * metadata.
     *
     * @see launcherUrlsMatch
     * @param url A launcher URL.
     * @returns @c true if the launcher was removed.
     */
    Q_INVOKABLE bool requestRemoveLauncherFromActivity(const QUrl &url, const QString &activity);

    /**
     * Return the list of activities the launcher belongs to.
     * If there is no launcher with that url, the list will be empty,
     * while if the launcher is on all activities, it will contain a
     * null uuid.
     *
     * URLs are compared for equality after removing the query string used
     * to hold metadata.
     */
    Q_INVOKABLE QStringList launcherActivities(const QUrl &url);

    /**
     * Return the position of the launcher with the given URL.
     *
     * URLs are compared for equality after removing the query string used
     * to hold metadata.
     *
     * @see launcherUrlsMatch
     * @param url A launcher URL.
     * @returns @c -1 if no launcher exists for the given URL.
     */
    Q_INVOKABLE int launcherPosition(const QUrl &url) const;

    /**
     * Request activation of the task at the given index. Derived classes are
     * free to interpret the meaning of "activate" themselves depending on
     * the nature and state of the task, e.g. launch or raise a window task.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestActivate(const QModelIndex &index) override;

    /**
     * Request an additional instance of the application backing the task
     * at the given index.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestNewInstance(const QModelIndex &index) override;

    /**
     * Requests to open the given URLs with the application backing the task
     * at the given index.
     *
     * @param index An index in this tasks model.
     * @param urls The URLs to be passed to the application.
     **/
    Q_INVOKABLE void requestOpenUrls(const QModelIndex &index, const QList<QUrl> &urls) override;

    /**
     * Request the task at the given index be closed.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestClose(const QModelIndex &index) override;

    /**
     * Request starting an interactive move for the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestMove(const QModelIndex &index) override;

    /**
     * Request starting an interactive resize for the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be a
     * no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestResize(const QModelIndex &index) override;

    /**
     * Request toggling the minimized state of the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleMinimized(const QModelIndex &index) override;

    /**
     * Request toggling the maximized state of the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleMaximized(const QModelIndex &index) override;

    /**
     * Request toggling the keep-above state of the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleKeepAbove(const QModelIndex &index) override;

    /**
     * Request toggling the keep-below state of the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleKeepBelow(const QModelIndex &index) override;

    /**
     * Request toggling the fullscreen state of the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleFullScreen(const QModelIndex &index) override;

    /**
     * Request toggling the shaded state of the task at the given index.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleShaded(const QModelIndex &index) override;

    /**
     * Request entering the window at the given index on the specified virtual desktops.
     *
     * On Wayland, virtual desktop ids are QStrings. On X11, they are uint >0.
     *
     * An empty list has a special meaning: The window is entered on all virtual desktops
     * in the session.
     *
     * On X11, a window can only be on one or all virtual desktops. Therefore, only the
     * first list entry is actually used.
     *
     * On X11, the id 0 has a special meaning: The window is entered on all virtual
     * desktops in the session.
     *
     * @param index An index in this window tasks model.
     * @param desktops A list of virtual desktop ids.
     **/
    Q_INVOKABLE void requestVirtualDesktops(const QModelIndex &index, const QVariantList &desktops) override;

    /**
     * Request entering the window at the given index on a new virtual desktop,
     * which is created in response to this request.
     *
     * @param index An index in this window tasks model.
     **/
    Q_INVOKABLE void requestNewVirtualDesktop(const QModelIndex &index) override;

    /**
     * Request moving the task at the given index to the specified activities.
     *
     * This is meant for tasks that have an associated window, and may be
     * a no-op when there is no window.
     *
     * This base implementation does nothing.
     *
     * @param index An index in this tasks model.
     * @param activities The new list of activities.
     **/
    Q_INVOKABLE void requestActivities(const QModelIndex &index, const QStringList &activities) override;

    /**
     * Request informing the window manager of new geometry for a visual
     * delegate for the task at the given index. The geometry should be in
     * screen coordinates.
     *
     * If the task at the given index is a group parent, the geometry is
     * set for all of its children. If the task at the given index is a
     * group member, the geometry is set for all of its siblings.
     *
     * @param index An index in this tasks model.
     * @param geometry Visual delegate geometry in screen coordinates.
     * @param delegate The delegate. Implementations are on their own with
     * regard to extracting information from this, and should take care to
     * reject invalid objects.
     **/
    Q_INVOKABLE void requestPublishDelegateGeometry(const QModelIndex &index, const QRect &geometry, QObject *delegate = nullptr) override;

    /**
     * Request toggling whether the task at the given index, along with any
     * tasks matching its kind, should be grouped or not. Task groups will be
     * formed or broken apart as needed, along with affecting future grouping
     * decisions as new tasks appear.
     *
     * As grouping is toggled for a task, updates are made to the
     * grouping*Blacklist properties of the model instance.
     *
     * @see groupingAppIdBlacklist
     * @see groupingLauncherUrlBlacklist
     *
     * @param index An index in this tasks model.
     **/
    Q_INVOKABLE void requestToggleGrouping(const QModelIndex &index);

    /**
     * Moves a task to a new position in the list. The insert position is
     * is bounded to the list start and end.
     *
     * syncLaunchers() should be called after a set of move operations to
     * update the launcherList property to reflect the new order.
     *
     * When the groupInline property is set to @c true, a move request
     * for a group member will bring all siblings along.
     *
     * @see syncLaunchers
     * @see launcherList
     * @see setGroupInline
     * @param index An index in this tasks model.
     * @param newPos The new list position to move the task to.
     */
    Q_INVOKABLE bool move(int row, int newPos, const QModelIndex &parent = QModelIndex());

    /**
     * Updates the launcher list to reflect the new order after calls to
     * move(), if needed.
     *
     * @see move
     * @see launcherList
     */
    Q_INVOKABLE void syncLaunchers();

    /**
     * Given a row in the model, returns a QModelIndex for it. To get an index
     * for a child in a task group, an optional child row may be passed as well.
     *
     * This easier to use from Qt Quick views than QAbstractItemModel::index is.
     *
     * @param row A row index in the model.
     * @param childRow A row index for a child of the task group at the given row.
     * @returns a model index for the task at the given row, or for one of its
     * child tasks.
     */
    Q_INVOKABLE QModelIndex makeModelIndex(int row, int childRow = -1) const;

    /**
     * Given a row in the model, returns a QPersistentModelIndex for it. To get an index
     * for a child in a task group, an optional child row may be passed as well.
     *
     * @param row A row index in the model.
     * @param childRow A row index for a child of the task group at the given row.
     * @returns a model index for the task at the given row, or for one of its
     * child tasks.
     */
    Q_INVOKABLE QPersistentModelIndex makePersistentModelIndex(int row, int childRow = -1) const;

    void classBegin() override;
    void componentComplete() override;

Q_SIGNALS:
    void countChanged() const;
    void launcherCountChanged() const;
    void launcherListChanged() const;
    void anyTaskDemandsAttentionChanged() const;
    void virtualDesktopChanged() const;
    void screenGeometryChanged() const;
    void activityChanged() const;
    void filterByVirtualDesktopChanged() const;
    void filterByScreenChanged() const;
    void filterByActivityChanged() const;
    void filterNotMinimizedChanged() const;
    void filterNotMaximizedChanged() const;
    void filterHiddenChanged() const;
    void sortModeChanged() const;
    void separateLaunchersChanged() const;
    void launchInPlaceChanged() const;
    void groupModeChanged() const;
    void groupInlineChanged() const;
    void groupingWindowTasksThresholdChanged() const;
    void groupingAppIdBlacklistChanged() const;
    void groupingLauncherUrlBlacklistChanged() const;
    void activeTaskChanged() const;

protected:
    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
    bool lessThan(const QModelIndex &left, const QModelIndex &right) const override;

private:
    Q_INVOKABLE void updateLauncherCount();

    class Private;
    class TasksModelLessThan;
    friend class TasksModelLessThan;
    QScopedPointer<Private> d;
};

}